1. Field of the Invention
The present invention relates to an agricultural baler including a weighing device and a compression chamber housing that is supported on a support axle with a possibility of vertical displacement relative thereto.
2. Description of the Prior Art
U.S. Pat. No. 4,362,097 discloses a round baler in which a wheel arm is pivotally connected to the compression chamber housing by a hydraulic cylinder. The hydraulic cylinder is equipped with a manometer for measuring the pressure. The hydraulic pressure serves as a measurement of weight of a bale in the baler. If the bale weight increases, the compression chamber housing is lowered relative to the support axle which causes run-in of the piston into the cylinder, whereby the hydraulic pressure is increased. The springiness of the compression chamber housing is insured only by the change of the oil volume. This limits the driving speed and causes high oscillation loads. A further drawback of such an arrangement consists in that it is one-sided, which results in imprecise weighing results. In addition, no device is provided which would correct false weighing results caused by transverse or longitudinal tilt of the baler. With a wide use of rented balers, even today, the number of compressed bales dominates the accounting basis for a farmer, renter and/or customer. For sound calculation, the exact knowledge of the bale weight is of a primary importance. Often, the bales are loaded on a transporting vehicle directly on the field. Here, the knowledge of the exact weight of bales is also very important, in particular, in order to prevent overloading.
Accordingly, an object of the present invention is to provide a baler with an increased precision of bale weighing.
Another object of the present invention is to provide a baler in which the measured bale weight is used for controlling different baler functions which permit to obtain, during the bale formation, pre-adjusted, reproducible bale weights.
These and other objects of the present invention, which will become apparent hereinafter, are achieved by providing springs at both sides of the compression chamber housing for supporting same on the support axle with a possibility of vertical displacement relative to the support axle, and sensor means for determining a distance between the compression chamber housing and the support axle, with the signals generated in response to sensing the distance representing a measure of a bale weight.
The baler according to the present invention is characterized by a simplicity of constructions, with the spring deflection of the baler serving for measuring the bale weight. In practice, the displacement measurement of the relative position of the compression chamber housing with respect to the support axle unexpectedly produced results that permit to evaluate how the displacement of the housing with respect to the support axle changes with time during which the bale is formed. Despite different disturbance variable, a steady increase of the measurement value takes place with the increase of bale weight. That permitted to achieve a precision of bale weighing of about 2%. The present invention is particularly advantageous for round balers because the gravity center direction does not change with the increase of the bale weight, so that no load sensors on the drawbar are needed.
According to a further development of the present invention the sensor means is formed of two displacement sensors arranged on the support axle in a spaced relationship to each other and selected from a group consisting of inductive distance sensors with a solenoid plunger, inductive analogue sensors, capacitance analogue sensors, potentiometric displacement sensors, path scanners, cable controlled displacement sensors.
In this case, practically, each wheel is associated with a corresponding displacement sensor. If the empty weight of the baler is set as a nil value of the weighing device, the mean value of both measured displacement variables obtained in the evaluation device produces directly a bale weight in a corresponding output device.
According to a further development of the present invention, there is provided an inclination sensor for determining inclination of the baler which produces a false weight measurement. The inclination sensor is connected with the evaluation device. This permits to obtain, because of corresponding correction coefficients contained in the evaluation device, an actual bale weight despite the longitudinal and/or transverse tilt of the baler.
In order to be able to utilize the present invention also in piston balers in which the center of gravity is displaced with increase of the bale weight, there is provided a sensor for sensing the drawbar supporting force acting on the baler and connected with the evaluation device. Thereby, the drawbar supporting force is taken into account in determining the bale weight.
An operator-friendly, constant and reproducible bale weighing can be achieved automatically in a baler with a constant cylindrical compression chamber for producing round bales when the actuation of a twine or net enveloping device dependent on the bale weight is effected directly or indirectly, by the weighing device upon the compression chamber housing being displaced by an amount corresponding to a desired pre-adjusted bale weight.
The provision of a displacement sensor on each side of the baler permitted to provide a particularly simple bale shape displaying device that shows, dependent of the deflections of each side of the compression chamber housing measured by a respective sensor, a non-uniform filling of the compression chamber in its side regions.
In response to this showing, the operator can take measures which would insure a uniform filling of the chamber.
According to a further embodiment of the present invention, there is provided an evaluation device connected with the sensor means and a device for determining an actual geographical position of the baler and connected with the global positioning system, with the actual position determining device being connected with the evaluation device for communicating thereto signals indicative of position data corresponding to actual bale weights during formation of a bale. There is further provided electronic memory means connected with the evaluation device. The evaluation device converting the received data, which indicate allocation of weight values of pick-up goods to respective positions of the baler, into digital yield mapping, with the mapped data being stored in the memory means for an electronic display and/or evaluation. The foregoing arrangement is particular suitable for yield mapping which is particularly useful in production of silage and/or formation of hay bales.
Because weighing can be conducted both during the formation of a bale, dynamic measurement, and during the stoppage of the baler, stationary measurement, the present invention provides for an automatic control of the weighing process. The research and experiments have shown that both the dynamic measurement and the stationary measurement give approximately identical results.
The present invention provides a baler with a spring-supported compression chamber housing which can operate at a speed above 50 km/hr, has simple means for measuring the weight-rendering spring deflection, insures an operator""s comfort, and provides means for connection of the weight measuring means with the global positioning system.
According to the invention, the same advantages are achieved when instead of measuring the displacement of the compression chamber housing, the frequency change of the oscillation system of the baler (springs/mass system) is measured. The frequency change likewise represents a measure of a bale weight. This is because the frequency changes with changing of the bale weight. Because the natural frequency of, e.g., round baler remains substantially constant during operation of the baler, the measurement of the frequency change permits to obtain suitable weight results.
The novel features of the present invention, which are considered as characteristic for the invention, are set forth in the appended claims, The invention itself, however, both as to its construction and its mode of operation, together with additional advantages and objects thereof, will be best understood from the following detailed description of preferred embodiment, when read with reference to the accompanying drawings.